Prior Taiwan application number 098201291, entitled “Disposable safety syringe structure,” was invented by the inventor of the present invention. In FIGS. 9 and 10 of prior Taiwan application number 098201291, the disposable safety syringe structure comprises a barrel 10, a needle hub 11 movably installed in the barrel 10, a plunger 12 movably inserted into the barrel 10 and having a plug head 121, and two positioning bases 101 disposed in the barrel 10 and having a snap slot 102 each, wherein the needle hub 11 has a connecting section 111, an elastic hook plate 112, and two protruding columns 113 corresponding to the snap slots 102 respectively and having a snap member 114 each. In the assembling process, the needle hub 11 is installed into the barrel 10, and the snap members 114 of the protruding columns 113 are embedded into the snap slots 102 respectively to achieve the positioning effect.
However, the aforementioned conventional safety syringe requires a precise embedment of the snap members 114 into the snap slots 102 to achieve the positioning effect, so that it takes a longer time for the installation process. Obviously, the conventional safety syringe requires further improvements. On the other hand, the needle hub 11, the plunger 12, and the barrel 10 are manufactured by plastic injection molding, so that the protruding columns 113 of needle hub 11 require a more complicated mold for the manufacture, and incur a higher cost.